Orthodontic appliances known as “Class II” devices are designed to correct malocclusions between the upper and lower teeth without requiring patient cooperation, and for this purpose are mounted for continuous use and not easily removed by the patient. So-called Herbst appliances are well known for this purpose.
Jasper U.S. Pat. No. 4,708,646 discloses an elastic element or jumper, such as a spring surrounded by a rubber core, and having metal end caps for attachment to and between braces attached to the patient's upper and lower teeth. This device has proven highly successful in Class II treatment. The Jasper jumper uses end caps that can swivel at their points of attachment, providing greater patient comfort, but the number of components in the jumper, e.g. spring, cover and end caps, can cause occasional failure.
Vogt U.S. Pat. No. 5,435,721 describes an orthodontic appliance that performs in the same manner as a Jasper jumper, but wherein the jumper takes the form of a unitary, thin band of material (such as metal) that can be connected between the braces associated with the patient's upper and lower teeth. The connecting device has a body that is substantially flat and rectangular, with bent end portions that are preferably rounded for purposes of comfort. Each end portion includes an aperture for attachment to the braces associated with the patient's teeth. According to Vogt, at least one of the apertures of each connecting device is preferably keyed so that upon its attachment to the braces, swivelling of the connecting device is effectively precluded on the theory that this reduces breakage. However, although the Vogt device offers the simplicity of a unitary metal strip as the jumper, in practice the Vogt device has inadequate strength at its ends, which tear and fracture at the points of attachment. A need remains for a jumper that is more resistant to breakage, yet comfortable for the patient to wear and effective for orthodontic use.